Blowout plug



Oct. 1. 1944). I M. G ..'MILLER BLOWOUT PLUG Filed Feb. 24, 1959 MEL w/vG. M/LLEB Patented Oct. 1, 1940 t. BLOWOUT PLUG Q I 4 Claims.

This invention relates to a blowout plug and has more particularrelation to a novel type of insert adapted to be readily inserted intothe jacket of the plug when necessary.

The plug has been particularly designed for use in boilers. The completeassembly embodies a jacket designed to be screwed upwardly through thecrown sheet of the boiler furnace and having an insert or filler offusible material which, in .case the water becomes too low in theboiler, will fuse and drop out allowing steam to enter the furnace toextinguish the fire and to prevent an explosion.

15 The usual blowout plugs, as at present constructed, comprise a metaljacket adapted to be screwed through the crown sheet of a furnace andfilled from end to end with a fusible material such as tin or leaddesigned to melt and drop out in case the water becomes too low. Forsafety 20 these plugs are changed from time to time for the reason thatafter they have been installed for a considerable length of time thecorrosion of the jacket may prevent the fusible filler from melting anddropping out as it is designed to do, and it is .common practice toremove the plugs and replace them from time to time. In as much as theconventional type of plug is filled from end to end with a fusiblematerial, it is not practicable to remove said material and reuse thejacket and hence there is considerable loss in discarding the plugs inas much as the complete plug, including the jacket, must be discarded.

It is one of the prime objects of this invention to provide a novel typeof filler for the jacket which, when it is desired to renew a plug, maybe removed from the jacket and a new one substituted so that the jacketmay be reused indefinitely, thus resulting in a great saving.

With the above and other objects in view, the

4 invention has particular relation to certain novel features ofconstruction, arrangement of parts and use, an example of which is givenin this specification and illustrated in the accompany- 45 ing drawing,wherein:

Figure 1 shows a longitudinal sectional view of the plug embodying theinvention and showing the same in position in the crown sheet, and

Figure 2 shows aside view of the filler or in- 50 sert designed to closethe bore through the jacket.

Referring now more particularly to the drawing wherein like numerals ofreference designate the same parts in each of the figures, the numeral 1indicates the jacket of the plug which is to somewhat longer than thejacket of the standard V i flM elvin G. Miller, Houston,Tex. I I'Application February 24, 1939, Serial No; 258,142 1- (011122-5043) plugcommonly used. At one end the jacket is formed with a polygonal head 2to receive a wrench whereby the jacket may be screwed through thethreaded aperture 3 of the crown sheet 4. The jacket has the externalthreads 5 which mesh with the threads of the aperture 3 as shown inFigure 1. The jacket has an axial bore 6 extending therethrough from itsouter to its inner end and of an approximately uniform diameter.However, the bore is slightly flared at its inner end as at I.

The numeral 8 designates an insert or plug formed of fusible materialsuch as tin or other suitable fusible material.

Before insertion into the jacket, the plug 8 is approximatelyfrusto-conical in form but at its large end it is flared at a slightlygreater pitch, than the flare of the main body of the plug as isindicated at 9, Figure 2. The diameter of the plug 8 adjacent the flaredportion 9 is slightly greater than the diameter of the bore 6 adjacentthe fiared portion 1 so that when the plug 8 is driven into the innerend of the jacket, a portion of said plug as Ill will assume a truecylindrical shape and when the plug is driven to home position theflared portion 9 will be fitted very closely into the seat 1 so thatthere will be no leakage of water between the filler or plug 8 and thejacket I and hence no corrosion will collect between the filler plug andthe jacket to prevent the plug from melting and dropping out in case ofexcessive heat.

When it becomes necessary to renew the plug the jacket may be screwedout of the crown sheet and the filler plug 8 knocked out and a new onesubstituted for it and the jacket may thus be used from time to timewith substantially no loss of material.

It will be noted that only a relatively small amount of material isrequired for the plug 8 since it closes only the inner end of the jacketand hence said plug may be very cheaply produced and readily supplied tothe users for replacement purposes as necessity may require.

The drawing and description disclose what is now considered to be apreferred form of the invention by way of illustration only, while thebroad principle of the invention will be defined by the appended claims.

What I claim is:

1. A blowout plug comprising an outer jacket having an axial bore ofapproximately uniform diameter extending therethrough from end to end, afusible filler plug adapted to be inserted into one end only of thebore, said filler plug tapering from its outer to its inner end and themargin, only, of the outer end thereof being slightly flared to form anannular fluid tight joint with the jacket when driven home into thejacket.

2. A blowout plug comprising an elongated jacket having a cylindricalbore of approximately uniform diameter extending axially therethrough,from end to end, a fusible insert, approximately frusto-conical in form,inserted into one end only of the jacket, the outer end of the insertbeing slightly flared and a portion of the insert adjacent said flaredend being deformed into a cylindrical shape to form a fluid tight jointwith the jacket when the insert is driven home.

3. An insert for the jacket of a fusible plug, said insert being formedof fusible material and being frusto conical in form and having itslarge end slightly flared at the margin only of said large end.

4. A blowout plug comprising an elongated outer jacket having acylindrical bore of approximately uniform diameter extending axiallytherethrough from end to end, a fusible filler plug approximatelyfrusto-conical in form adapted to be inserted into one end only of thebore, said end of said bore being annularly! .chamfered and thecorresponding marginal end of the filler plug being flared, said fillerplug having a portion adjacent the flared end deformed into acylindrical shape and fitting closely in the bore and said flared endfitting closely in the chamfered portion of the bore, when the fillerplug is driven fully home into the bore, the cylindrical portion and theflared portion of the plug forming a fluid tight joint with the jacket.

7 MELVIN G. MILLER.

